The present invention is generally related to the field of scanning technology and, more particularly, is related to a system and method for scanning documents using charge coupled devices.
Current scanning technology now facilitates scanning of color documents and the like to create a digital document therefrom. The digital document or, a hardcopy document reduced to digital form, may then be displayed on an appropriate display device such as a cathode ray tube (CRT), etc. Computer systems provide significant flexibility to users to manipulate or change a digital document in a myriad of ways.
In order to generate the digital document from a hardcopy document, the hardcopy document is typically run through a scanner at a slow speed while the scanner acquires a dense pattern of pixels from the document by sampling values on sensors as they acquire the reflection of white light that strikes the hardcopy document. To acquire full color digital images, each of the pixels is preferably sampled by three sensors, where the reflected light that strikes each of the three sensors is filtered by one of three filters that allows a single color of light to pass therethough. These filters may isolate specific colors, such as, for example, red, green, and blue.
The sensors employed are quite dense, providing a number of pixels of up to 600 per inch and greater. Thus, there is a significant amount of pixel color component data that is created and processed during the scanning of a particular image. Consequently, it takes a significant amount of time to scan and process a specific hardcopy document to obtain a color digital image of the same.
In light of the foregoing, the present invention provides for a system and method to control an acquisition of a number of pixels in a scanning system. According to one embodiment, the system provides an interface circuit that includes a multiplexer to route at least one color component of one of a number of pixels to a register. The multiplexer comprises at least three color component inputs to receive at least three color components for each of the pixels. The system also includes logic to control a selection signal applied to the multiplexer and a sample signal applied to the register. The selection and sample signals control the acquisition of at least one color component according to a color acquisition sequence.
In another embodiment, the present invention provides a method for acquiring of a number of pixels in a scanning system. Broadly stated, the present method includes the steps of: generating a number of color components associated with a number of pixels of an image; selecting at least one of the color components associated with a respective one of the number of pixels, the selection being made according to a color acquisition sequence; and storing the at least one of the color components selected in a memory.
In still another embodiment, the present invention provides for a system to control an acquisition of a number of pixels in a scanning system. The present system includes at least three registers, each register having an input to receive a color component associated with one of a number of pixels from a charged coupled device (CCD) sensor. Each of the registers includes a sample signal input that receives a sample signal that triggers the acquisition of the color components. The system also includes a multiplexer having a number of inputs, the color component from each of the at least three registers being applied to one of the inputs. The multiplexer also includes a selection input to receive a selection signal. The present system further includes logic to generate the selection signal applied to the selection input and the sample signal applied to the sample signal input. Both the selection signal and the sample signal are generated according to a color acquisition sequence. The color acquisition sequence ultimately causes an acquisition of a number of color components that is less than a total number of color components in an image.
Finally, in yet another embodiment, the present invention provides a method for acquiring of a number of color components associated with a number of pixels of an image in a scanning system. Broadly stated, the present method includes the steps of: generating the number of color components associated with the number of pixels of the image; acquiring all of the color components associated with one of the pixels simultaneously, selecting at least one of the color components acquired simultaneously for each of the pixels; and storing the color components selected in a memory, wherein a total number of color components selected is less than a total number of color components associated with the image.